1. Field of the Invention
The present invention concerns a portable mechanical ironing machine for household use in particular.
2. Description of Related Art
Mechanical ironing machines consisting basically of a fixed lower ironing plate and a movable upper ironing plate designed to be lowered in such a way as to mate with a lower one and press against it and hence against the garments appropriately placed between them, simultaneously applying heat generated electrically by electrical resistances embedded therein are well known.
The use of springs designed to apply pressure to the ironing plate during the ironing step acting together with the manual effort applied to a handle or grip used for moving the upper ironing plate between the open or separating position with respect to the lower plate and the closed position with respect to the lower plate is also known.
In this respect and in relation to mechanical ironing machines in which the upper plate is hinged to a base bearing the fixed lower plate and in the hinge or joint section of which is housed a compression spring capable of assuming two stable positions, passing through a neutral point, in one of these positions the spring holds the upper plate in the open position while in the other position it applies the closing and ironing force.
Finally, various solutions have been proposed for shifting the spring, or rather its axis, and hence its support, from one of the positions to the other, using the operating handle or grip of the movable ironing plate.
According to a first solution, a translation of the handle or grip parallel to itself brings about the aforesaid shifting by means of a kinematic sector gear and rack mechanism. This mechanism is rather complicated and hence is costly to produce industrially, as well as costly to maintain and repair. It is well known that one of the basic requirements of an apparatus, especially of the household appliance type, is to reduce maintenance as much as possible and simplify it to the highest degree.
Another substantially equivalent solution is provided for in Swiss Pat. No. 501764 in which the operating or control handle of the movable ironing plate is connected to a kinematic mechanism which comprises a connecting rod which engages the support of the aforesaid spring. Rotation of the handle around its own axis of fastening to the upper ironing plate causes, through a crank mechanism, translation of the spring support between the aforesaid two positions.
This solution, while solving the problem itself, does not solve other problems which are also connected with the abovementioned accomplishments, problems which may be briefly summarized as follows:
1. The above handle or grip must complete a rather long stroke, pivoting through angles of 90 degrees and more. This means that the length or amount by which the handle may protrude beyond the upper ironing plate must be considerably reduced, consequently reducing the length of the lever arm and increasing the force which must be applied.
2. The abovesaid shifting of the spring support between the two positions mentioned involves the application of a force which is not constant but varies in the course of the shifting, with values which may be considerable, whereas one of the requirements of equipment of this kind is to require minimal and steady forces.
3. Since this is portable equipment, means must be provided to absolutely prevent opening of the ironing machine during transportation.
It is true that the abovementioned Swiss patent provides for a latch, but there is no assurance that this latch will not release as a result of incorrect handling of the equipment.